What is the value of cos(25)cos(65)-sin(25)sin(65) ?

The value of cos(25)cos(65)-sin(25)sin(65) is 0

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cos(25)cos(65)-sin(25)sin(65)

cos (2 5^{\circ}) cos (6 5^{\circ}) - sin (2 5^{\circ}) sin (6 5^{\circ})

0

Solution steps

cos (2 5^{\circ}) cos (6 5^{\circ}) - sin (2 5^{\circ}) sin (6 5^{\circ})

Rewrite using trig identities:

cos (9 0^{\circ})

= cos (9 0^{\circ})

Use the following trivial identity:

cos (9 0^{\circ}) = 0

= 0

1 - cos^{2} (0)

tan (- \frac{9 π}{4})

tan (6 9^{\circ})

tan (\frac{31 π}{6})

40 \cdot sin (6 0^{\circ})

What is the value of cos(25)cos(65)-sin(25)sin(65) ?
The value of cos(25)cos(65)-sin(25)sin(65) is 0